linux-kernel - [PATCH v3 5/9] backlight: qcom-wled: Override default length with qcom,enabled-strings

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Date:   Mon, 15 Nov 2021 21:34:55 +0100
From:   Marijn Suijten <marijn.suijten@...ainline.org>
To:     phone-devel@...r.kernel.org, Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Lee Jones <lee.jones@...aro.org>,
        Daniel Thompson <daniel.thompson@...aro.org>,
        Jingoo Han <jingoohan1@...il.com>
Cc:     ~postmarketos/upstreaming@...ts.sr.ht,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@...ainline.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Martin Botka <martin.botka@...ainline.org>,
        Jami Kettunen <jami.kettunen@...ainline.org>,
        Pavel Dubrova <pashadubrova@...il.com>,
        Marijn Suijten <marijn.suijten@...ainline.org>,
        Kiran Gunda <kgunda@...eaurora.org>,
        Bryan Wu <cooloney@...il.com>, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linux-fbdev@...r.kernel.org
Subject: [PATCH v3 5/9] backlight: qcom-wled: Override default length with qcom,enabled-strings

The length of qcom,enabled-strings as property array is enough to
determine the number of strings to be enabled, without needing to set
qcom,num-strings to override the default number of strings when less
than the default (which is also the maximum) is provided in DT.

This also introduces an extra warning when qcom,num-strings is set,
denoting that it is not necessary to set both anymore.  It is usually
more concise to set just qcom,num-length when a zero-based, contiguous
range of strings is needed (the majority of the cases), or to only set
qcom,enabled-strings when a specific set of indices is desired.

Fixes: 775d2ffb4af6 ("backlight: qcom-wled: Restructure the driver for WLED3")
Signed-off-by: Marijn Suijten <marijn.suijten@...ainline.org>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@...ainline.org>
---
 drivers/video/backlight/qcom-wled.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/video/backlight/qcom-wled.c b/drivers/video/backlight/qcom-wled.c
index ab10910971e9..5306b06044b4 100644
--- a/drivers/video/backlight/qcom-wled.c
+++ b/drivers/video/backlight/qcom-wled.c
@@ -1520,6 +1520,8 @@ static int wled_configure(struct wled *wled)
 				return -EINVAL;
 			}
 		}
+
+		cfg->num_strings = string_len;
 	}
 
 	rc = of_property_read_u32(dev->of_node, "qcom,num-strings", &val);
@@ -1530,9 +1532,13 @@ static int wled_configure(struct wled *wled)
 			return -EINVAL;
 		}
 
-		if (string_len > 0 && val > string_len) {
-			dev_err(dev, "qcom,num-strings exceeds qcom,enabled-strings\n");
-			return -EINVAL;
+		if (string_len > 0) {
+			dev_warn(dev, "Only one of qcom,num-strings or qcom,enabled-strings"
+				      " should be set\n");
+			if (val > string_len) {
+				dev_err(dev, "qcom,num-strings exceeds qcom,enabled-strings\n");
+				return -EINVAL;
+			}
 		}
 
 		cfg->num_strings = val;
-- 
2.33.1